Progressive ambulation and treadmill testing of patients with acute myocardial infarction during hospitalization: a feasibility study.

Symptoms, signs, hemodynamic and electrocardiographic responses of 12 patients with acute myocardial infarction were studied before, during and after three activities: activity I, sitting upright; activity II, walking to the adjacent toilet; and activity III, walking on a treadmill set at 1.2 mph (1.9 km/hr) at 0, 3 and 6% successive gradients. The three activities were studied respectively at three, six and ten days (means) after infarction. Weakness was the most commonly occurring symptom. Mean systolic blood pressure fell 9 mm Hg upon assumption of the upright position (activity I) and was sustained for the five minutes of sitting. The systolic blood pressure drop was only 3.5 mm Hg with activity II. During activity III, one patient developed angina. Between rest and the 6% treadmill gradient, systolic blood pressure, heart rate and pressure-rate product rose 29 mm Hg, 26 beats/minute and 64 units, respectively. Electrocardiographic evidence of ischemia was observed in two patients during activity I, in two patients during activity II, and in one patient during activity III, but was insufficient for stopping the activities. Similarly, two patients developed minor arrhythmias, one with activity I and one with activity III. The use of this low-level treadmill test before discharging the patient from the hospital proved to be safe and feasible for obtaining objective data to assess the patients' ability to perform activities requiring equal exertion at home. Successful performance of these three activities before leaving the hospital should provide useful criteria for discharge of a patient with myocardial infarction.